High molecular weight, homogeneous, branched copolymers of maleic anhydride and alkyl vinyl ether monomers

ABSTRACT

What is described is a high molecular weight homogeneous, branched copolymer of maleic anhydride and a C 1 -C 5  alkyl vinyl ether monomer, in which a branching agent is present in an amount of less than 0.5 wt. % of the polymer. A solution process of making such polymer also is described.

BACKGROUND OF THE INVENTION

1. 1. Field of the Invention

2. This invention relates to copolymers of maleic anhydride and alkylvinyl ethers, and more particularly, to high molecular weight,homogeneous, branched copolymers of such monomers, and to a solutionprocess of making these polymers, and then use in denture adhesivecompositions and personal care formulations.

3. 2. Description of the Prior Art

4. Copolymers of maleic anhydride and alkyl vinyl ethers are well knownin the art. Often, such polymers are prepared by precipitationpolymerization in a solvent having a low chain transfer constant, suchas benzene or cyclohexane. For example, high molecular weight, linearcopolymers of methyl vinyl ether and maleic anhydride can be prepared byprecipitation polymerization in benzene, and drying. Usually suchprecipitation process can be conducted at only a low solids levels, e.g.20% solids or less.

5. Accordingly, it is an object of this invention to provide highmolecular weight, homogeneous, branched copolymers of maleic anhydrideand alkyl vinyl ethers.

6. Another object of this invention is to provide a solutionpolymerization process to prepare such high molecular weight,homogeneous, branched copolymers of maleic anhydride and alkyl vinylether monomers, in solvents other than benzene, and at a high solidslevels, i.e. greater than 30%.

7. These and other objects and features of the invention will be madeapparent from the following description of the invention.

SUMMARY OF THE INVENTION

8. What is described herein is a high molecular weight, homogeneous,branched copolymer of maleic anhydride and a C₁-C₅ alkyl vinyl ethermonomer, in which the polymer chains are branched with a branching agentpresent in an amount of less than 0.5 wt. % of the polymer. Suitablepolymers herein include those in which the maleic anhydride component ispresent in the form of its half-ester or diacid derivatives, having amolecular weight of greater than 100,000, preferably greater than500,000. These polymers are made as a solution of the polymer at aconcentration greater than 30% solids, in a non-benzene solvent such asacetone.

9. The copolymers of the invention are particularly useful in personalcare and oral care compositions, for example, in denture adhesivecompositions which include about 30-40% by wt. of the polymer.

DETAILED DESCRIPTION OF THE INVENTION

10. In accordance with the present invention, there is provided a highmolecular weight homogeneous, branched polymer of maleic anhydride and aC₁-C₅ alkyl vinyl ether monomer, in which the polymer chains arebranched with a branching agent present in an amount of less than 0.5wt. % of the polymer.

11. As a feature of the invention, there is provided herein a solutionpolymerization process of making such copolymers. The process includespolymerizing maleic anhydride and an excess of an alkyl vinyl ether over1:1 stoichiometry of the monomers, in a non-benzene solvent, in thepresence of a branching agent present in an amount of less than 0.5 wt.% of the resultant polymer. A preferred non-benzene solvent is acetone,although other solvents in which the reaction product is soluble arealso suitable, such as tetrahydrofuran, N-methyl pyrrolidone and thelike.

12. As another feature of the invention, the process can be carried outat a >30% solids level.

13. Following polymerization, the resultant polymer can be converted tothe half-ester or diacid derivative, if desired.

14. Suitable branching agents are those having a reactivity about thesame as maleic anhydride so that all the branching agent and maleicanhydride are consumed in the presence of excess alkyl vinyl ether.

15. Suitable branching agents include phenylene and/or alkyldimaleimides, dimaleic anhydrides and alkyl divinyl ethers.

16. The molecular weight of the copolymer product of the invention isgreater than 100,000, preferably greater than 500,000 and, mostpreferably, greater than 1,000,000.

17. A preferred alkyl vinyl ether is methyl vinyl ether.

18. After completion of polymerization, the excess alkyl vinyl ether canbe removed to provide the desired polymer in solution.

19. The copolymers of the invention are used in personal care and oralcare compositions, for example, in denture adhesives which include about30- 40% by wt. of the polymer.

20. The invention will now be described with particular reference to thefollowing examples, in which:

EXAMPLE 1 Copolymer of Maleic Anhydride-Methyl VinylEther+N,N′-1,3-Phenylenedimaleimide (mole ratio 49.975:50.025:0.025)

21. A 2-liter stainless steel high pressure reactor was charged with513.88 g of acetone and 0.201 g of N,N′-1,3-phenylenedimaleimide. Thereactor was sealed and purged three times with nitrogen gas ending witha head pressure of 25 psi N₂. Then the temperature was raised to 70° C.during a 40 min period. When the temperature reached 60° C., 111.88 mlof molten maleic anhydride was introduced. At 80° C., separate feeds of175.35 ml of methyl vinyl ether and 1.17 g of decanoyl peroxide in 33 gof acetone were introduced into the reactor over a period of 3 hours,with the methyl vinyl ether feed begun 10 min. before the decanoylperoxide-acetone solution. After the feed was completed, the reactor wasmaintained at 80° C. for an additional half-hour. The reactor was thencooled to provide a thick, viscous light amber colored solution of thedesired copolymer product in acetone.

EXAMPLE 2

22. The process of Example 1 was carried out at a polymerizationtemperature of 70° C. After polymerization was complete, the maleicanhydride polymer product was hydrolyzed with excess water to providethe maleic anhydride diacid derivative of the copolymer. Then the diacidwas neutralized using 70 mol % CaCO₃ and 10 mol % Na₂CO₃ as follows: To580.61 of the copolymer solution containing 19.281 % solids of thediacid polymer in water a slurry of 44.988 g CaCO₃ and 6.812 g Na₂CO₃ in300 g water was added under high agitation during 2 days. The productwas the salt form of the diacid polymer which was oven-dried to providethe polymer in solid form.

EXAMPLE 3

23. The process of Example 1 was repeated using only 0.585 g of decanoylperoxide. The anhydride copolymer product was then converted to thediacid derivative and its salt, as in Example 2.

EXAMPLE 4

24. The process of Example 1 was repeated at 75° C. to provide theanhydride copolymer which was then converted to its diacid derivativewhich was converted to its salt by neutralizing 450.53 g of the polymersolution (diacid 22.08% solids in water) with 40.018 g CaCO₃/6.053 gNa₂CO₃/120.27 g water, using 217.87 g water for transfer of the saltinto the kettle.

COMPARATIVE EXAMPLE

25. The process of Example 1 was repeated except that theN,N′-1,3-phenylenedimaleimide reactant was omitted. The resultantanhydride copolymer was converted to its diacid and salt derivative asin Example 2. TEST RESULTS EXAMPLE NO. VISCOSITY* MW** 2 6.86 1.48 × 10⁶3 15.09 2.57 × 10⁶ 4 3.60  9.5 × 10⁵ Comparative 3.21  3.7 × 10⁵

26. While the invention has been described with particular reference tocertain embodiments thereof, it will be understood that many alterationsand modifications may be made which are considered within the scope ofthis invention and which will become apparent from the foregoingdisclosure.

What is claimed is:
 1. A high molecular weight homogeneous, branchedpolymer of maleic anhydride and a C₁-C₅ alkyl vinyl ether monomers, inwhich the polymer chains are branched with a branching agent present inan amount of less than 0.5 wt. % of the polymer.
 2. A polymer accordingto claim 1 in which the maleic anhydride is present in the polymer inthe form of the half-ester or diacid derivatives.
 3. A polymer accordingto claim 1 in which the molecular weight is greater than 100,000.
 4. Apolymer according to claim 1 in which the molecular weight is greaterthan 500,000.
 5. A polymer according to claim 1 wherein the molecularweight is greater than 1,000,000.
 6. A solution of the polymer of claims1 or
 2. 7. A solution according to claim 6 at greater than 30% solids.8. A solution according to claim 6 in which the solvent is acetone.
 9. Apersonal care or oral care composition including the polymer of claims 1or
 2. 10. An oral care composition according to claim 9 which is adenture adhesive composition.
 11. A solution polymerization process ofmaking the polymer of claims 1 or 2 which comprises polymerizing maleicanhydride and an alkyl vinyl ether in a non-benzene solvent in thepresence of a branching agent present in an amount of less than 0.5 wt.% of the resultant polymer.
 12. A process according to claim 11 in whichthe solvent is acetone.
 13. A process according to claim 11 in which thepolymerization provides a homogeneous solution of the copolymer in thesolvent.
 14. A process according to claim 11 which is carried out atgreater than 30% solids.
 15. A process according to claim 11 in whichthe polymer is converted to the half-ester or diacid derivative.
 16. Aprocess according to claim 11 in which the branching agent is aphenylene and/or alkyl dimaleimide; dimaleic anhydride or an alkyldivinyl ether.
 17. A process according to claim 11 in which thebranching agent is phenylene dimaleimide.
 18. A process according toclaim 11 in which the molecular weight is greater than 100,000,preferably greater than 500,000, most preferably greater than 1,000,000.19. A process according to claim 11 including the step of removing theexcess alkyl vinyl ether after polymerization is complete.